Monthly Churn to Annual Churn: Formula and Worked Examples
By Ulas ArslanPublished Updated
To convert a constant monthly churn rate to an annual rate, calculate 1 − (1 − monthly churn)^12. Do not simply multiply by twelve. Each month’s loss applies to what remains of the starting customer or revenue base, so the annual result compounds.
Think in retained share first
If monthly churn is 2%, the retained share is 98%. After one month, the starting base is multiplied by 0.98. After two months, it is multiplied by 0.98 twice. After twelve months, the retained share is 0.98^12, or about 0.7847.
Subtract that retained share from one to find cumulative churn. The same mathematics can describe customer-count loss or gross recurring-revenue loss, but those are different inputs. Choose one and keep it consistent. An unweighted customer churn rate is not automatically a revenue churn rate.
Worked monthly-to-annual examples
These figures are mathematical scenarios, not industry benchmarks. They assume a constant monthly rate, no reactivations and no additions to the starting base. Values are rounded after the full calculation.
| Monthly churn | Annual retention | Annual churn |
|---|---|---|
| 0.5% | 94.16% | 5.84% |
| 1.0% | 88.64% | 11.36% |
| 2.0% | 78.47% | 21.53% |
| 3.0% | 69.38% | 30.62% |
| 5.0% | 54.04% | 45.96% |
What this means for a revenue scenario
Take a fictional starting base of €100,000 in monthly recurring revenue. If gross revenue loss were a constant 2% per month, with no expansion or new sales included, about €78,472 of that starting monthly revenue base would remain after twelve months.
That ending MRR is not the total revenue collected over the year. Calculating cumulative revenue requires adding the retained revenue for each billing period and defining when losses take effect. The difference matters when explaining an annual forecast to someone who sees “€78,472” and assumes it represents twelve months of sales.
At a hypothetical 1% monthly loss rate, about €88,638 of the same starting monthly base would remain. The roughly €10,166 difference describes the gap between two assumptions. It is not evidence that a specific intervention would save that amount.
When monthly churn changes
If you have twelve different monthly churn rates for the same continuing cohort, multiply their retained shares: annual retention = (1 − c1) × (1 − c2) × … × (1 − c12). Annual churn is one minus that product.
Do not automatically apply this to twelve headline churn rates calculated from changing company-wide customer bases. New customers, reactivations and customer mix can change those denominators. To measure the actual annual result, follow the annual starting cohort directly.
For example, a business with annual contracts may have most cancellations in one part of the year. A smooth monthly rate hides that timing. The customer retention calculation guide explains how to keep the cohort consistent.
Use the formula in a spreadsheet
If cell A2 contains a monthly churn percentage, enter =1-(1-A2)^12 and format the result as a percentage. For an annual rate in A2, enter =1-(1-A2)^(1/12) to calculate its constant monthly equivalent. Check that A2 contains 2% rather than the number 2.
Keep a note beside the output stating the period, whether the input follows customers or revenue, and whether expansion is excluded. For revenue analysis, the GRR versus NRR guide explains that boundary.
CLE Index provides a separate way to explore customer revenue retention over 12, 24 and 36 months. Use it to compare stated scenarios, not to claim that a constant historical churn rate predicts every future period. The calculations above are directly reproducible arithmetic.